1. Field of the Invention
This invention relates to a magnetic recording and reproducing apparatus provided with a magnetic tape loading device, and more particularly is directed to a video tape recorder of the so-called helical scanning type used for audio recording with the pulse code modulation (PCM) system.
2. Description of the Prior Art
A conventional helical scan, cassette-type magnetic tape recording and reproducing apparatus has a tape guide drum mounted on the chassis of a magnetic head unit which includes a rotary magnetic head or heads mounted coaxially with the drum, and the magnetic tape is guided in an inclined path about the outer periphery of the drum so that the rotary magnetic head or heads operating at a high rpm, trace inclined or skewed tracks on the tape for recording and/or reproducing information signals in such tracks.
Such magnetic recording and reproducing apparatus is provided with a loading unit whereby the magnetic tape is extracted from a tape cassette mounted in an operative position within the recording or reproducing apparatus and is wrapped about the outer periphery of the drum. The loading unit is comprised of rotary members, such as loading rings, provided with loading blocks in turn equipped with deflection guide or inclined guide members for the magnetic tape. By the controlled rotation of these rotary members, the guide members of the loading unit may be transferred from inside the tape cassette to loading end positions in the vicinity of the tape guide drum.
The conventional recording or reproducing apparatus is also provided with a control electric motor for driving the rotary members and a switch for detecting the position of the loading blocks. Further, the magnetic recording or reproducing apparatus is provided with a pinch roller control unit for establishing or releasing pressure contact between the capstan and the pinch roller. The pinch roller control unit has the pinch roller mounted at one end of a supporting arm the other end of which is pivotally supported. The pinch roller is pressed against the capstan with the tape interposed therebetween in response to angular displacement of the supporting arm by, for instance, a solenoid plunger. In addition, the apparatus is designed so that the constant speed running of the magnetic tape may take place while the pinch roller is in pressure contact with the capstan (pinch ON state) and the tape stop (STOP), rewind (REW) or fast feed (FF) may take place while the pinch roller is released from pressure contact with the capstan (pinch OFF state).
When the loading unit and the pinch roller control unit are constructed as separate units, as in the above described conventional cassette-type magnetic tape recording or reproducing apparatus, separate driving sources are required for the loading and the pinch roller control units, resulting in an increased number of component parts and a complicated structure for the recording or reproducing apparatus. Further, the assembling operation is complicated and the apparatus can be made small and compact only with considerable difficulties. In addition, when the loading block and the pinch roller are driven by separate driving units, the chances of troubles or malfunctions are enhanced because of the independent manner of operation of the driving units, with the result that operational reliability is necessarily lowered.